Treatment of hydrocarbons with hydrogen chloride gas and oxygen

ABSTRACT

Heterocyclic compounds containing nitrogen are removed from hydrocarbon oils by treatment with oxygen (preferably in the form of air) and hydrogen chloride gas. The hydrocarbons may be treated alone, or a solvent may be used which assists in precipitating the complex of heterocyclic compounds formed by the reaction of the present invention. A preliminary heat-treating step makes the compounds even more susceptible to treatment by the present process. The products are worked up by neutralization and distillation or hydrofining. Improved oxidation resistance and color are obtained by the treatment of the present invention.

United States Patent Esso Research and Engineering Company [21 Appl. No. [22] Filed [45] Patented [73] Assignee [54] TREATMENT OF HYDROCARBONS WITH HYDROGEN CHLORIDE GAS AND OXYGEN 11 Claims, 3 Drawing Figs.

[52] US. Cl 208/254, 208/281 [51] Int. Cl C10g 17/02 [50] Field of Search 208/254, 241,225,281, 256,299, 177, I89, 196

[56] References Cited UNITED STATES PATENTS 2,063,517 12/1936 Morrell et al. 208/225 2,087,525 7/1937 Morrell et al....... 208/225 2,352,236 6/1944 Thomas 208/254 2,800,427 7/1957 Junk, Jr. et al 208/254 2,984,617 5/1961 DeChellis 208/21 1 3,085,061 4/1963 Metrailer 208/281 3,370,000 2/1968 Gilbert et al. 208/254 3,053,756 9/1962 Nottes et al 208/189 ABSTRACT: Heterocyclie compounds containing nitrogen are removed from hydrocarbon oils by treatment with oxygen (preferably in the form of air) and hydrogen chloride gas. The hydrocarbons may be treated alone, or a solvent may be used which assists in precipitating the complex of heterocyclic compounds formed by the reaction of the present invention. A preliminary heat-treating step makes the compounds even more susceptible to treatment by the present process. The products are worked up by neutralization and distillation or hydrofining. lmproved oxidation resistance and color are obtained by the treatment of the present invention.

TREATMENT OF HYDROCARBONS WITH HYDROGEN CHLORIDE GAS AND OXYGEN DESCRIPTION OF THE INVENTION It has long been know that the presence of nitrogen compounds in petroleum products has deleterious effects, the deleterious effects varying with the product. The nitrogen compounds which are involved principally occur as heterocyclic ring compounds, which in turn are generally divided into two classes referred to as acidic and basic (or nonacidic) nitrogen types. The acidic types occur in higher proportion and are much more difficult to remove. While both types cause instability, the acidic types are especially susceptible to oxidation and cause sludge formation and color instability.

The hydrogenation of oils containing heterocyclic nitrogen compounds does not completely cure the problem. Although the hydrogen-treated oils may have an initially satisfactory color, under ordinary storage conditions the color rapidly degrades and becomes unsatisfactory for sale to commercial customers. Further, such hydrofined fractions used as lube oils exhibit poor stability under the exposure to air and heat suffered during use as lubricating oils. However, by the present invention, the heterocyclic nitrogen compounds can be removed and, after hydrogenation, the thus-treated oils are entirely satisfactory for lubricating oil service.

Treatment of hydrocarbon oils with hydrogen chloride gas is not new. However, in the past, it has not been recognized that the presence of oxygen is absolutely necessary if the nitrogenous compounds are to be removed by precipitation. As will be later shown, blanketing of the hydrocarbon oil to exclude oxygen prevents the reaction from taking place. For the first time, then, the present invention provides a process utilizing hydrogen chloride and oxygen in admixture for the treating of hydrocarbon oils to obtain a rapid and substantially complete precipitation of heterocyclic nitrogen compounds.

The process of the present invention may be carried out with or without the presence of water. In order to decrease corrosion of equipment, water is preferably excluded. Aqueous hydrochloric acid 37 percent) and air can be used for precipitation of most of the nitrogen complex, and the final precipitation carried out with HCl gas. As a practical matter, however, the amount of water present in the treating system due to moisture in the air should be no greater than 0.1 weight percent (based on the oil). Under the conditions of the present process, the basic nitrogen compounds react with the hydrogen chloride gas to form amine salts such as hydrochlorides. The acidic nitrogen compounds are removed as a nitrogen complex, the complete nature of which is not fully understood. However, the nitrogen complex is heavier in specific gravity and higher boiling than the parent materials. This allows separation by decantation processes or by distillation processes.

The feature of difference in specific gravity may be used for separation by gravity settling, centrifugation, or the use of liquid cyclones. Aids, such as supersonic vibration, exposure to shock waves, or the use of an electrical field, may also be employed to speed up separation and to improve efficiency. Added coagulants or the addition of inert solids of suitable particle size and shape may also be used to assist in the entrapment and settling of the precipitate.

In order to understand the present invention, the various aspects will be hereinafter discussed in sequence; namely, the oils which are satisfactory feedstocks for treatment, the solvents which may be used to promote precipitation, the manner in which the oxygen and hydrogen chloride treatment is carried out, and the manner in which the products are finished.

FEEDSTOCKS The feedstocks of the present invention are hydrocarbon oils boiling generally within the range from 250 F. to 1200 F. (as converted to 760 mm). The invention has particular application to the treatment of oils in the lubricating oil range, from 600 F. to l l50 F. Generally, however, the invention has apnitrogen compounds such as indoles and pyrroles, for example, lubricating oils, feedstocks to cracking operations (such as catalytic crackers, steam crackers, thermal crackers), fuel oil, aromatic extracts, and gasolines.

Exemplary of lubricating oil stocks which may be treated by the present invention are those which are derived from Tia Juana crude from Venezuela. As will be shown in Examples 1, 2 and 3, the process of the present invention has been successfully applied to the treatment of a total lube oil cut which includes some asphalts, a I02 S.S.U. cut, and a 55 S.S.U. cut. in each of these cases, light hydrocarbon was used as a nonsolvent to assist in the precipitation of the nitrogenous compounds. The inspection data on the three lubricating oil samples from Tia Juana crude are shown below in Table I. The 102 S.S.U. and 55 S.S.U. oils were treated as shown hereinafter in Examples 1 and 2 and were hydrofined as shown in Examples 4 and 5 to obtain satisfactory oils having very good color and color stability and lower Conradson carbon tests, indicating better oxidation stability.

TABLE I Total Inspection out 102 SSU 55 SSU Flash, 000, F 166 515 450 Viscosity at- F., SSU 5, 050 2, 502 591 210 F., SSU 157 106.7 57. 3 Gravity, API 16.3 18. 7 20.3 Pour point, F 30 +5 25 Nitrogen, basic, weight percent 0. 021 O. 034 Nitrogen, non-basic, weight percent 0. 049 0. 103

Total, weight percent 0. 36 O. 170 0. 137

Sulfur, weight percent. 2. 1 1. 8 1.6 Color, ASTM Dark Dark Dark Conradson carbon 5.6 1.00 08 Silica gel, analysis:

saturates 45. 0 40. 0 44.0 42.7 6. 1 3. 5

The feedstocks to cracking units, such as a catalytic cracking unit, are generally obtained by fractionation of crude oils to obtain a so-called virgin gas oil boiling within the range from 400 F. to 1200 F., and having inspection data such as that shown below in Table II. Also shown in Table II are data on an exemplary fuel oil boiling within the range from 350 to 650 F. and a gasoline boiling from 90 to 430 F., all of which may be treated by the process of the present invention.

TABLE II Inspection Get feed Fuel oil Gasoline Flash, Pensky, F 243 122 Gravity, API 28.1 36 55. 3 Boiling range, F., percent:

1.6 430 IBP 368 1B1 00 750 50% 536 50% 212 1,150 FBP 650 90% 300 FBI 430 Sulfur, weight percent 0.32 0. 82 0. 54 Nitrogen, weight percent 0. 34 0. 09 0. 04 Combustion analysis:

Carbon, weight percent.. 86. 7 Hydrogen, weight percent 12, 9

The present invention may also be applied in improving the color stability of aromatic oils which have been obtained by extraction; for example obtained extracting a lubricating distillate fraction with phenol, furfural, S0 dimethysulfoxide or other selective solvent which removed aromatics, separating the aromatic extract from the solvent and recovering the aromatic extract. An exemplary aromatic extract is shown below in Table lll.

'lAllLF Ill Aromotiv. Inspection extract Flush, (,()C, F. 385 (ilavity,All 11.2 Viscosity, SS U ttlr 100 F 9, 26.5 210 F 115 Pour point, 35 (,olor Dark Distillation, converted to 750 mm.,

percent:

720 830 J5 936 Conradson carboiL. 0.57 Sulfur, weight percent 0. 62 Nitrogen, weight percent 1. 30

NONSOLVENTS The present invention may be carried out without the use of any added hydrocarbons whatsoever, the precipitate forming naturally in the hydrocarbon oil being treated. However, particularly in the case of aromatic extracts, the solubility of the reaction products is that the use of a paraffinic type hydrocarbon which acts as a nonsolvent is preferred.

The material chosen to act as a nonsolvent (or precipitatepromoting organic solvent) should be capable of being uniformly dispersed in the oil, preferably actually being miscible with the oil, but exhibiting very poor solubility for the precipitate (referring, of course to the conditions chosen for carrying out the operation). The nonsolvent should be substantially different in volatility from the hydrocarbon oil so that the nonsolvent can be separated from the oil by simple distillation. it has been found that the greatest nonsolvent effect on the nitrogen complex is found in selected isoparaffins or in the very low molecular weight normal paraffms or saturated ring hydrocarbons. Beta-substituted isoparaffins, such as Z-methylpentane or 2,2-methylbutane or 2,4-dimethylpentane, represent isoparaffmic types best suited to precipitate the complex. Propane, butane, pentane hexane, etc., are also effective and when natural naphthas contain predominantly mixtures of normal and isoparaffins in the C to C range, these naphthas may be used as solvents. Exemplary of the nonsolvents which can be employed are the to C normal and isoparaffins, which isooctane being particularly preferred for use with the lubricating oil fractions and isohexane being particularly preferred for use in the treatment of aromatic oils. Other suitable solvents are commercial C mixed aliphatic hydrocarbons, commercial C mixed aliphatic hydrocarbons, varnish makers and painters naphtha, petroleum ether, cyclopentanes or cyclohexanes, and liquefied petroleum gas (an admixture of butane, isobutane and propane). H

Nonsolvents (such as water) which are immiscible both with the oil and the precipitate and which can be saturated with HCl will carry out an extraction of undesirable basic hydrochlorides as well as promoting precipitation of the complex PRETREATM ENT If desired, the feedstock may be heat treated to change the ratio of basic nitrogen compounds to nonbasic nitrogen compounds. Normally in the feedstocks contemplated, this ration will be in the range from 0.25 to 0.35. This ratio can be increased by heat treating at temperatures from 400 to 650 F. (preferably 550 F.) for a period of one-half to 3 hours (preferably 1 HOUR) in the presence of acidic or basic solids, such as a bed of sand, activated silica gel, CaO, Portland cement or magnesia. Heat treating of a typical feedstock in the presence of Portland cement for one-half hour at 600 F. changed the ratio from 0.29 to 0.99 Suitably, the heat pretreatment can be carried out by passing the heated feedstock through the solid bed at a space velocity chosen to provide the desired residence time. The bed will gradually become inactivated by deposition of carbonaceous material which can be periodically burned from the bed in a regeneration step. At least 300 volumes of feedstock can be passed through the bed per volume of solid before regeneration, and probably as much as lOOO volume per volume, depending upon the nature of the feedstock, the temperature and residence time employed, and the nature of the solid in the bed.

PROCESS OF TREATING The process of the present invention is carried out by contacting the feedstock with air and hydrogen chloride gas. The more paraffmic feedstocks my contain from 0 to 3 volumes of a nonsolvent per volume of feedstock, and where the feed stock contains more than 40 percent aromatic hydrocarbons, the use of from 0 to 8 volumes of nonsolvent per volume of oil is preferred. The treatment may be carried out by first contacting the oil with air and thereafter contacting the oil with an admixture of air and HCl without the prior contacting of the oil wit air, or the oil may be contacted alternately first with one treating agent and then with the other. It is to be understood that, although air is preferred in the present invention, molecular oxygen may be employed instead. ln some cases metal chlorides such as ferric or zinc chloride may be used with HCl as promoters for the reaction and to reduce the solubility of the complex which is formed.

In carrying out the present invention, the treating zone should be maintained under a temperature from 0 to 300 F., preferably 75 F., and a pressure from atmospheric to 250 p.s.i.g., preferably from atmospheric to 30 p.s.i.g., all chosen to maintain the hydrocarbon product in the liquid phase. As will be understood, the range of suitable feedstocks makes it possible to use a large number of combinations of conditions. However, since the reaction goes well at ambient temperatures and pressures, for economy it is preferred to operate at ambient temperature and pressure.

The hydrocarbon oil may be saturated with oxygen first by contacting it with air, if desired, for a period (depending on the capacity of the reactor, the temperature and pressure, the viscosity and boiling range of the feed) from 0.5 minute to several hours (preferably 15 minutes) at an air-to-oil volume ratio from 0.01 to 3 volumes/volume per minute (preferably 0.2 volumes/volume per minute). The air/vapor mixture should be kept outside of the explosive range After this pretreatment is completed, the oil is contacted with an admixture of air and HCl gas (or with HCl gas alone) for a period (depending on relevant variables) from 1 second to several hours (preferably 30 minutes) at a total gas stream-to-oil volume ratio from 0.01 to 3 volumes/volume per minute (preferably 0.2 volumes/volume per minute; and at a ratio of hydrogen chloride gas to air so that the oil liquid phase is saturated with air. The contacting conditions are chosen to saturate the oil with an excess of reagent and vary with composition of the oil.

By using the procedure of the present invention, a copious precipitate is obtained which is an oxidation product of products from the families of indoles, pyrroles and carbazoles, and possibly other heterocyclic nitrogen compounds, which are present in the hydrocarbon feedstock. It is believed that they are polymerized by the oxidation reaction and thus form insoluble precipitates.

WORKUP AND HYDROFINING OF TREATED PRODUCT The treated product contains some residual HC] which must be removed or neutralized in order to avoid an acid catalyzed decomposition of the resulting product. To that end, therefore, after a precipitate has been separated from the oil by decanting, filtration, or other means, the oil is neutralized by contact with an aqueous solution of an alkali (such as NaOl-l, CaO, Ca(OH) Na CO NaHcO ammonia gas, NH OH, etc.). Prior to chemical neutralization, a saturated salt water contacting step removes excess HCl in a gaseous form in which it is easily recovered, and thereby reduces chemical treating costs. The neutralized oil may then be water washed and subsequently hydrofined in order to obtain a highly desirable product having good color and excellent color and oxidative stability. Alternate removal steps may be vacuum stripping with or without inert gas sparge or inert gas stripping without vacuum.

The hydrofining step is conventional in the art and may be carried out in contact with catalyst such as cobalt molybdate under conditions including a temperature from 450 to 650 F. (preferably 575 F.), a pressure from lS0to 3000 p.s.i.g. (preferably 750 p.s.i.g. a hydrogen feed rate from to I500 s.c.f./B (preferably 500 s.c.f./B), and at a space velocity of 0.1 to 10 volumes of oil per volume of catalyst per hour (preferably l v./v./hr.). The hydrofining is carried out in the liquid phase. As exemplary of the types of equipment which may be used for separating the precipitate from the oil, three types of continuous operations are shown in the drawings wherein:

FIG. 1 discloses a continuous upflow separator;

FIG. 2 shows a distillation column for carrying out both the precipitation and separation operations; and

FIG. 3 shows a continuous process for carrying out the invention In FIG. 1 is shown a continuous upflow separation zone which provides both settling and filtration. The settler 100 is seen to comprise two sections, a filtration section and a settling section. The filtration section comprises two zones; a coarse packing 101 e.g., Raschig rings of about 2 inches nominal size) and a fine packing e.g., Raschig rings having a /-inch diameter nominal size). The mixture of precipitate and oil from the reaction zone is introduced into the zone 100 by way of line 104, and, by reason of baffles 106, which operate to reduce turbulence, the precipitate settles to the bottom and is withdrawn as a slurry through the line 108. The oil rises and is withdrawn by way of line 110. Any small particles of the nitrogen complex are removed by contact with the coarse or fine packing, which thus act as filters. The packing may be backwashed periodically in order to prevent plugging of the filtration zone.

The interior of the settler may be lined with nonpolar films such as polytetrafluoroethylene, polyethylene, polypropylene, wax, etc., since it has been found that nitrogen complexes will not adhere to surfaces coated with these films. Possibly two of the settling zones will be operated in parallel so that continuous operations may be carried out in one of the settlers while the other is being backwashed.

In FIG. 2 is shown a variation wherein a fractionating tower 200 is used to separate the oil from the precipitate. The admixture of oil and precipitate is introduced by way of line 202, and the nitrogen complexes, being higher boiling than the parent oil, settle to the bottom of the fractionating tower and are removed in line 204 as a slurry stream. The oil is withdrawn, preferably by way of a side stream 206, and the solvent, if any, may be removed by way of line 208, so that the separation of solvent is carried out at the same time that the precipitate is removed. 0

In FIG. 3 is shown as continuous settling zone used in combination with an orifice mixture, wherein the oil is introduced by way of line 302, air by line 304, and hydrogen chloride by way ofline 306. The oil, air and l-lCl are admixed in an orifice mixer 308 and the admixture is passed by way of line 310 into the settling zone 300. In the settling zone 300 air and unreacted hydrogen chloride are removed by way of line 312, the sludge settles and is removed by way of line 314 and the treated oil is removed by way ofline 316.

Thus, it is seen that the present invention may be carried out continuously by the use of well-known equipment.

In order to illustrate the present invention, the following examples are given.

EXAMPLES Example I.

An admixture of 8,003 g. of a Tia Juana lubricating oil distillate having a viscosity of 102 to I07 S.S.U. at 210 F. with 3,477 g. of isooctane (92 percent purity-no aromatics) was prepared. This master batch was split into four separate charges of about 2,870 g. each, which were separately charged into vertical glass tube reactors containing a side tube for gas introduction at the bottom. A ground glass joint at the top could be opened for charging but closed during the reaction. The ground glass side tube at the top was connected to a condenser to reflux vaporized solid, and noncondensable gases were passed through two dry ice traps and water washed down the drain. Two thermometers were provided for measuring liquid temperature and vapor temperature near the top of the reactor.

After charging the unit at ambient temperature (about 75 F.), air was passed through the unit; and after a period of air treatment, HC1 gas from the cylinder was added to the air stream for passage through the unit. Both of the gas streams were at ambient temperature. The air treatment was carried on HCl an unmeasured rate in excess of that required for precipitation) for a period of about 15 minutes, after the admixture of air and HCl was passed through the mixture for an additional 30 minutes. The total treat rate of HCl and air was about 10 cc./min., the HCl rate being 50 cc./min. As quickly as each HCl and air mixture contacted the oil, a copious darkcolored precipitate immediately began to form. Formation of the precipitate continued for about 5 minutes after introduction of the HCl/air mixture and was continued for the total of 30 minutes to be sure that all of the compounds would be removed. A slight temperature rise of about 4 F. was noted in the liquid phase, which is probably the net balance of a positive heat of solution, a negative heat ofevaporation, and what may be either a positive or negative heat of reaction.

The dark-colored precipitate from compound indicated of the four runs was allowed to accumulate and the oil simply decanted through a fiberglass filter, followed by paper finishing filtration. Total precipitate at the end which had accumulated in the reaction vessel was washed three times with normal pentane, drained and weighed. The yield of rough precipitate was about 4.5 percent based on the weight of oil charged. This corresponds very closely to the reported 6.1 weight percent of polar compounds (principally nitrogen and sulfur heterocyclic compounds) indicated for this oil by silica gel analysis and as shown in table I.

The combined treated and separated oil (8,182 cc.) plus about 1,000 cc. of normal pentane (which was added to reduce viscosity) was contacted with a solution containing 5 liters of water and 96 g. of anhydrous sodium carbonate in order to neutralize residual acidity in the oil. The oil was poured into the aqueous solution with stirring, and was mixed with the solution for about 30 minutes until the indicator paper showed the solution to be essentially neutral.

The neutral oil was separated and water washed four times and dried over anhydrous calcium sulfate. The oil was later hydrofined as shown in example 4 EXAMPLE 2 The procedure of Example I was followed in treating a 55 S.S.U. oil obtained from Tia Juana crude and similar results were obtained. The 55 viscosity oil contained 0.17 weight percent nitrogen by neutron activation, and after treatment it was shown to contain 0.03 weight percent nitrogen (the lower limit of the test: the actual nitrogen content may have been lower). The treated oil contained 0. [9 percent oxygen which appeared to be dissolved molecular oxygen. The precipitate from the treated oil was shown to contain 3.1 weight percent nitrogen and 2.6 percent oxygen. Calculated on the basis of the nitrogen in the precipitate, about 91 percent of the total nitrogen compounds in the feedstock were removed by the present invention. EXAMPLE 3 The procedure of Example 1 was followed in treating a lube oil out from Tia Juana crude, as shown in Table l. After treatment it was found that the feedstock nitrogen content was reduced from 0.36 weight percent to 0.14 weight percent in the lube oil fraction, with the precipitate containing 0.81 weight percent nitrogen.

EXAMPLE 4 The treated oil of example 1 was subjected to hydrotining in contact with cobalt molybdate catalyst under the following conditions:

Temperature, 575 F.

Pressure, 750 p.s.i.g.

Hydrogen treat rate, 500 s.c.f./Bbl.

LHSV, 1.0 The treated product had an excellent color and excellent oxidative stability, as is shown below in Table IV, following example 5.

EXAMPLE-5 The treated oil of example 2 was submitted to hydrofining under the same conditions as those chosen for treating the oil of example 1. Excellent results were also obtained in treating this oil, and the product had excellent color and oxidative stability as shown below in table IV.

TABLE IV 55 102 Inspection of hydrofined oils viscosity viscosity Flash, COC, F 455 520 Viscosity, SSU at 100 F... 466 1,810 210 54. "2 93.9 Gravity, API 22. 2 20. 4 Pour point, F 30 5 Nitrogen, weight percent basic .011 030 Nitrogen, weight percent, non-basic .019 084 Total, weight percent 0. 03 .114

Sulfur, Weight percent 1. 3 1. 22 Color, ASTM 1. 5 1 3. o Colorhold, ASTM 24 hours at 212 2. 5 1 4. 5 Silica gel analysis:

saturates 52. 2 48. 2 Aromatics. 43. O 44. Iolars 2. 3. 0

1 Light EXAMPLE In order to show that the presence of air is absolutely necessary, the procedure of example 1 was followed in the treatment of a 55 vis Tia Juana lube oil distillate except that the reaction zone was blanketed with nitrogen in order to exclude air. The amount of precipitate formed was quite small and nitrogen removal was not detectable.

Having disclosed my invention, what 1 wish to cover by Letters Patent should be determined not by the specific examples herein given but only by the appended claims.

1 claim:

1. A process for removing acidic heterocyclic nitrogen compounds from a hydrocarbon oil which comprises, in the absence of catalysts:

intimately contacting said hydrocarbon oil in the liquid phase with a stream of air for a period of 0.5 minute to 3 hours at a rate of 0.01 to 3 volumes of air per volume of hydrocarbon oil per minute, whereby said hydrocarbon oil is saturated with oxygen, thereafter intimately contacting said hydrocarbon oil for a period of 1 second to 3 hours with a stream of an admixture of HCl gas and air at a rate of 0.01 to 3 volumes of admixture per volume of hydrocarbon oil per minute until a dark precipitate forms, the ratio of HCl gas to air being from 1:10 to 10:1 and separating said precipitate from said hydrocarbon oil.

2. A process in accordance with claim 1 wherein the ratio of HCl gas to air is about 1:1

3. A process in accordance with claim 1 wherein the contacting step is carried out at a temperature from 0 to 300 F. and a pressure from 0 to 250 p.s.i.g.

4. A process in accordance with claim 3 wherein the temperature is about 75 F. and the pressure is from 0 to 30 p.s.i.g.

5. A process of reducing the acidic heterocyclic nitrogen compound content of hydrocarbon oil boiling within the range from 250 to 1,150 F. which contains indoles and pyrroles and their derivatives, said method comprising in the absence of catalysts,

at a temperature from 0 to 300 F. and a pressure from atmospheric to 250 p.s.i.g.,

contacting said hydrocarbon oil first with a stream of air for 0.5 minute to 3 hours at an air-to-oil volume ratio from 0.01 to 3 volumes of air per volume of oil per minute and then with an admixture of air and HCl gas for 1 second to several hours.

at a total gas stream-to-oil volume ratio from 0.01 to 3 volumes of gas per volume ofoil per minute and at an HCl-to-air volume ratio from 1:10 to 10:1, so that the oil phase is saturated with oxygen,

whereby a dark precipitate is obtained, and separating said hydrogen oil from said precipitate.

6. A process in accordance with claim 5, wherein the contacting temperature is about 75 F., the contacting pressure is about 0 to 30 p.s.i.g., the air contact time is about 15 minutes, and air-to-oil volume ratio is about 0.3, the air-HCl contact time is about 30 minutes, the total gas stream-to-oil volume ratio is about 0.2, and the HCl-to-air volume ratio is about 1 7. A process in accordance with claim 6, further comprising the step of neutralizing said separated hydrocarbon oil.

8. A process in accordance with claim 7, further comprising the step of hydrofining the neutralized oil under conditions including a temperature from 450 to 650 F., a pressure from to 3,000 p.s.i.g., and a space velocity from 0.1 to 10. 9. A process in accordance with claim 8, wherein the hydrofining ions include a temperature of about 575 F., a pressure of about 750 p.s.i.g., and a LHSV of about 1 v./v./hr.

10. A process for removing acidic heterocyclic nitrogen compounds from a hydrocarbon oil which comprises,

contacting said hydrocarbon oil with a solid chosen from the group consisting of silica, activated silica gel, calcium oxide, Portland cement and magnesia, at a temperature from 400 F. to 650 F. for a period of0.5 to 3 hours,

intimately contacting the thus heat treated hydrocarbon oil in the liquid phase with a stream of air for a period 0.5 minute to 3 hours at a rate of 0.01 to 3 volumes of air per volume of hydrocarbon oil per minute, and

thereafter intimately contacting said hydrocarbon oil for the period of 1 second to 3 hours with a stream of an admixture of HCl gas and air at a rate of 0.01 to 3 volumes of admixture per volume of hydrocarbon oil per minute, until a dark precipitate forms, the ratio of Hcl gas to air being from 1:10 to 10:1, and

separating said precipitate from said hydrocarbon oil.

11. A process in accordance with claim 10 wherein the solid is Portland cement and the heat treatment is carried out at about 600 F. for about one-half hour. 

2. A process in accordance with claim 1 wherein the ratio of HCl gas to air is about 1:1.
 3. A process in accordance with claim 1 wherein the contacting step is carried out at a temperature from 0* to 300* F. and a pressure from 0 to 250 p.s.i.g.
 4. A process in accordance with claim 3 wherein the temperature is about 75* F. and the pressure is from 0 to 30 p.s.i.g.
 5. A process of reducing the acidic heterocyclic nitrogen compound content of hydrocarbon oil boiling within the range from 250* to 1,150* F. which contains indoles and pyrroles and their derivatives, said method comprising in the absence of catalysts, at a temperature from 0* to 300* F. and a pressure from atmospheric to 250 p.s.i.g., contacting said hydrocarbon oil first with a stream of air for 0.5 minute to 3 hours at an air-to-oil volume ratio from 0.01 to 3 volumes of air per volume of oil per minute and then with an admixture of air and HCl gas for 1 second to several hours. at a total gas stream-to-oil volume ratio from 0.01 to 3 volumes of gas per volume of oil per minute and at an HCl-to-air volume ratio from 1:10 to 10:1, so that the oil phase is saturated with oxygen, whereby a dark precipitate is obtained, and separating said hydrogen oil from said precipitate.
 6. A process in accordance with claim 5, wherein the contacting temperature is about 75* F., the contacting pressure is about 0 to 30 p.s.i.g., the air contact time is about 15 minutes, and air-to-oil volume ratio is about 0.3, the air-HCl contact time is about 30 minutes, the total gas stream-to-oil volume ratio is about 0.2, and the HCl-to-air volume ratio is about
 1. 7. A process in accordance with claim 6, further comprising the step of neutralizing said separated hydrocarbon oil.
 8. A process in accordance with claim 7, further comprising the step of hydrofining the neutralized oil under conditions including a temperature from 450* to 650* F., a pressure from 150to 3,000 p.s.i.g., and a space velocity from 0.1 to
 10. 9. A process in accordance with claim 8, wherein the hydrofining ions include a temperature of about 575* F., a pressure of about 750 p.s.i.g., and a LHSV of about 1 v./v./hr.
 10. A process for removing acidic heterocyclic nitrogen compounds from a hydrocarbon oil which comprises, contacting said hydrocarbon oil with a solid chosen from the group consisting of silica, activated silica gel, calcium oxide, Portland cement and magnesia, at a temperature from 400* F. to 650* F. for a period of 0.5 to 3 hours, intimately contacting the thus heat treated hydrocarbon oil in the liquid phase with a stream of air for a period 0.5 minute to 3 hours at a rate of 0.01 to 3 volumes of air per volume of hydrocarbon oil per minute, and thereafter intimately contacting said hydrocarbon oil for the period of 1 second to 3 hours with a stream of an admixture of HCl gas and air at a rate of 0.01 to 3 volumes of admixture per volume of hydrocarbon oil per minute, until a dark precipitate forms, the ratio of Hcl gas to air being from 1:10 to 10:1, and separating said precipitate from said hydrocarbon oil.
 11. A process in accordance with claim 10 wherein the solid is Portland cement and the heat treatment is carried out at about 600* F. for about one-half hour. 